Not sure if you guys are allowed to answer this or not but I'll ask anyways.

Does development on RB itself work like this:

While a version (eg R3) has been officially released, the next version (R4) is being tested and bug-squished, while development on the version after that (R5) has been started?

From some of the feedback reports I've ready, it seems that even right after a public release, the next version is already in its final candidate stages, so I was wondering if you guys always have two versions in the works: the first for the beta testers and to be the next public release, and one after that which could be called an experimental release where new features are being added (before the bugs from the previous are started to be worked on).

I hope it's something like that. If not, I would not at all be against RS taking the full 90-days between releases (unless a critical bugfix is needed of course).

The transition from r3 to r4 went straight into fc (almost) because we knew that we had some large issues to resolve quickly. So we wanted to keep the turn-around time low, and the best way to do that is to not introduce new features.

That being said, we usually work on releases in a linear fashion. Large new features do get rolled-along under the hood from release to release though. So while huge new feature Foobar may not be in release R, it could have some of its work done under the hood and not-exposed, and it'll come along in release R+1 in an exposed fashion.